Device for making hollow bodies of sheet metal under hydraulic pressure



' H. E. KRANENBERG DEVICE FOR MAKING HOLLOW BODIES OF SHEET Aug. 18,1953 METAL UNDER HYDRAULIC PRESSURE 5 Sheets-Sheet 1 Filed F eb. 15,1952 El -1 4m x I INVENTOR. ennui! M [G E. KRANENBERG 2,649,067

' H. DEVICE FOR MAKING HOLLOW BODIES OF SHEET METAL UNDER HYDRAULICPRESSURE 5 Sheets-Sheet .2

Aug. 18, 1953 Filed Feb. 15, 1952 r P 35 5 p:

' INVENTOR.

I grew'we "Aug. 18, 1953 H. E. KRANENBERG 2,649,067

DEVICE FOR MAKING HOLLOW BODIES 0F SHEET METAL UNDER HYDRAULIC PRESSUREv Filed Feb. 15, 1952 5 Sheets-Sheet 3 0 I 1 IIIIIIIIIII'IIII'IIII I I II 1 I I I I 1 1 I I 1 1 I TI 1 INVEN TOR.

WSW K 8, 1953 H. E. KRANENBERG DEVICE FOR MAKING HOLLOW BODIES OF SHEETMETAL UNDER HYDRAULIC PRESSURE Filed Feb. 15, 1952 5 Sheets-Sheet 4 vF127. 5 F 7. 7 w sf w s sf Inf Aug. 18, 1953 H. E. KRANENBERG DEVICE FORMAKING HOLLOW BODIES OF SHEET METAL UNDER HYDRAULIC PRESSURE 5Sheets-Sheet 5 Filed Feb. 15, 1952 A man be man INVENTOR.

Fatentecl Aug. 18, 1953 ENT OFl-"CE' DEVICE FOR MAKIN G HOLLOW 7 BODIES. 0F

SHEET METAL) UNDER I-HZ'DRAULILT PRE S'- SURE Application February 'lfi,1952, SeriaINo. 271,659 In Germany'December 16, 1949 4nGlaims- (Cl.113-44 'I'liepresent-inventionrelates to a device for making orformi'nghollow bodies ofi sheet= metal under hydraulic pressure in' general, andsuch device which permits of suclr fcf rming preferably in onesingle-step:

It is known in theiorming of hollow bodies from a plain sheet metalto-=pre'ssthe latter into a dieby-* subjectingthe face of the" sheetmetal disposed opposite to the recess of thed'ie to h y draulicpressure; the sheet metal beingclamped between the die and a cover,thereby pressing-'- the sheet metal into the diee at the'same timeexpanding the sheetmetal;-

This method brings about the disadvantagethat; particularlyif the"d'raw-ihg of thesheet metal is' of appreciable length;- the tliielmessof the sheet metal is so mucli redu'c'ed that bruises and foldsare---formedand even often a tearing; of the sheet metal occurs.

Ithas been-proposed; therefore; to clamp the sheet metal yieldinglibetween twoelastic plates and't'o feed theliydraulic fluid-of highpressure into-apressing bag. This; method}- however, can"- be used'only'if the-pressing forces are-compara tively small; thatmeans,ill-00111166121611" with verythinmetalsheets and small" bodies; sincethe pressing-bag is destroyed very easily-otherwise It'lias -a'lso'beenproposed to performtfie pressing step of cylindrical bodies; which havebeen' subjectedto apreliminarystep; by-subjecting*the'- thus preparedcylindrical body directly to the pressing fluid, filling tliedieitself'al'sowitkflixid" which escapes; d'ueto the exertion of the-pressure"force: Yet; iirthis' case,- itisnecessary for'sealing purposes toprovide wide andunyielding-ed'ges of the workpiece which areclampedbetween the sealing faces so-that the forming" of the hollow bodyis achieved only Icy-reducing of the-thick ness of the sheet metal.

It is; therefore;- one object of" the present invention to provide"- a-'device for the-'- forming of hollow bodies which permits of the'-formingby means of direct application ofa hydraulic fluid simultaneouslywith-aliydrauli'c' counter pressure and also to form-insuch mannerthat'the slieet' metal: is 'drawnu. without reducing the thickness ofthe'. metal brought about: by. applib'ationofthe pressure forces.

It isanoth'eu. object of the: present: invention to provide adeviee: forforming? of 'hollowsbodies in. which anslotsis disposed: between the sumrt ing faces ofzfthesdie?andithatiot its cove'xf, theeslot bein:,c1osed: up:- outwardly and. of: such dimen-- sions that the pressurefluid form a;

veil:betweentherguiding...faces for' thei edge of 55 bodiestwhichincludes -a isealingt, ringhdisposedf on the sheet. metal and: which:is; adapted to seal: a guide: slot connected with; a pressure: chamber,the=said:sealing ring preventingalso apimovement of: the metal:sheetsxa'ndi being; of at shape-moms plementarystoitheshape oti'thebodyvtozbe formed;

It is .still a:;tur.ther. object: o'frthepresent invenetion'v to providea'- device: ion forming. Of'jh'OllOW. bodies: which. includes; sealing;rings: disposedi. onv the metal:- sheets and: adjustable in. accordancewitmthese thickness: ofzthei. metalasheets,z thexedgesi of the: metal.sheets being: covered by. a: thin liquid iv'eil' and... the:SaidTLseal-ing; rings: permitting acont'rol 43f Lthe :fIiCfiODiencountered by the :sheet edge; thereby? permitting: the. formingv of:bodies: in one.co1d1-.step; which otherwisefwouldft require severalsuccessive steps.

It. is: yet. an object: of; the. present: invention to: provideaideviceior formingiotihollowi bodies includes. sea-ling; rings disposedin the: die.

below-'rthe drawn-radiir It has: been. found that the drawing: way for:

thev hollow: bodies. iscomparatively limited? when such;.additionalsealing. rings. aretz'provid'edziimthe die below thedraw-radii. because? the wall; ofz the: hollow body is; pressedtowardithe .wall. of. the: die tby hydraulic' pressureg therebypreventing the; sliding movement of the; metal. sheet, and; tears: or:the like occur in: the: bottom. portionv of th'e' body.v

It. is;..therefore;:. yet another object: of the pres-.- entinventionto. provide a; device for forming: of. hollow bodies:.in-wliich easealinggringqis'sprovided below the: draw-1 adii'. the die randa agl1id8 S10t is disposed. in the: forming-.- portion of: the die in orderto? provide a .thin: liquid/veil betweenxth'e die: wall; and: the wallor the? workpiece::

It is still arrv object 'of' the 'present invention; to? provide adevice for" forming hollow. bodies -v which includes a" deep di'awauxiliarypiston liaving-- a= diameter which" differs from" the diameter"This is brought about of the deep-draw member for slightly more than thethickness of the meta1 sheet.

It is also an object of the present invention to provide a device forforming of hollow bodies, in which, in the form-shaping portion of thedie, liquid of predetermined pressure is provided to create a hydrauliccounter-pressure, the said liquid being pressed into slots disposedbetween the die wall and that of the body to be formed, thereby forminga liquid veil favoring the sliding of the workpiece in vertical workingdirection.

It is still another object of the present invention to provide a devicefor forming of hollow bodies which comprises a movable bottom die towhich the workpiece is formed at first and which movable die starts itsdownward movement after wards.

It is still another object of the present invention to provide a devicefor forming of hollow bodies, in which the hydraulic fluid is fedthrough the deep-draw piston while the liquid creating thecounter-pressure is fed through the form die which includes a channelfor feeding the counterpressure liquid to its wall, the latter beingpreferably equipped with a longitudinally extending slot, therebypermitting the feeding and distribution of the counter-pressure liquidinto the draw-space.

It is yet another object of the present invention to provide a devicefor forming of hollow bodies, having a movable forming die, the latterbeing formed as differential piston, the portion having the smallerdiameter being guided along the forming walls.

It is still an object of the present invention to provide a device forforming of pre-formed, hollow bodies, which includes sealing sleevesdisposed at the ends of the die and extending into the end of the hollowbody as Well as abutting the inner wall of the hollow body uponapplication of pressure, thereby providing means for forming of barrels,conically shaped hollow bodies, vase-shaped bodies or urns, merelyrequiring to pre-form the sheet metal to a cylinder or to a truncatedcone, the sealing sleeves being preferably of rubber or other elasticmaterial.

It is still an object of the present invention to provide such devicefor forming of hollow bodiesv in which device just one such rubbersleeve is provided, which rubber sleeve is formed to a ring whichextends at an angle to the inner wall of the hollow body, particularlywhen pressure up to 100 atmospheres is applied, while in case of formingof such metal sheets which require a pressure of more than 100atmospheres, the sleeve is formed in such manner that a cover of a discabuts the inner wall of the sleeve flange, the disc being mounted on thefeeding pipe for the pressure liquid.

It is also known to produce hollow bodies from a pre-formed cylindricalbody, as used for milk cans or milk jugs and bottles, yet the forming ofsuch bodies requires appreciable work in the drawing process and alsosome time loss brought about by the necessary following glowing anddipping of the workpiece after each drawing step.

It is, therefore, still another object of the present invention toprovide a device for forming of hollow bodies which permits of the coldforming of such hollow bodies in one single step. Ihis is achieved byusing a pre-formed workpiece in which a divided core is inserted and thefree edge of the workpiece which extends over the end portion of thefinished workpiece is .removed by means of a guide slot provided in theformed, by example, as folding screws.

which surrounds the'mentioned extension and which coincides with theguiding slot.

A device is also known in which the means receiving thepressure forcebetween the die and its cover comprises bolts which are disposedparallel to the pressure force and which bolts may be An unequaltightening of these screws or bolts, respectively, causes easily a foldformation or tearing of the metal sheet to be worked.

It is, therefore, still an object of the present invention to provide adevice for forming of hollow bodies in which the pressure fluid is usedin such manner that the pressure fluid itself may be used for themechanical locking of the die.

cover movable in guides and secured by a special;

locking means. Such formation permits the use of comparatively largepressure forces without interfering with the arrangement of themultiplicity of locking means.

It is yet another object of the present invention to provide a devicefor forming of hollow bodies comprising a block having a guide for thecover in which locking means are disposed, which look-- ing meanspenetrate the cover, thereby providing a centralization of the coverduring its mechanical movement.

It is yet another object of the present invention to provide a flangeextending in peripheral direction from the top of the cover, and piston.

rods extending from hydraulic lifting cylinders are secured to thesaidfiange of the cover in order to permit of a fast opening and closingmovement of the die by using the available hydraulic liquid.

It is still another object of the present invention to provide a devicefor forming-of hollow bodies which comprises a framework which 'in-.cludes hydraulic lifting cylinders andwhich in cludes hydraulic pressurecylinders for,-'thelocking means of the cover, the framework support ingan exchangeable block which receivesthe die.

With these and other objects in view, whichwill become apparent in thefollowing detailed description, the present invention will be clearlyunderstood in connection with, the accompany-;

Fig. 2 is a sectional elevationof a second embodiment of the presentinvention;

Fig. 3 shows the sectional elevation of anem-v bodiment disclosing ahydraulic forming device for deep-forming of hollow bodies;

3a is a fragmentary section of the die in dicatlng the space between theworking sheet metal and the shoulders of the forming member.

Fig. 4 is a sectionalelevation of the embodiment shown in Fig. 3 at adifferent stage of the forming process; v v M Fig. 5 shows a sectionalelevation of the embodiment disclosed. in Fig. 3- at-the endof theforming process;

Fig. 6 shows an axial section of an embodi ment for forming of barrelbodies with inserted core;

Fig. 7 shows an axial section of the embodiment shown in Fig. 6 in whichthe workpiece has been widened to barrel shape;

Fig, 8. shows the axial section of the embodiment' shown in Fig. 6: witha varied form of the die for the forming of barrels;

Fig. 9 is an axial section of the device for forming of hollow bodieshaving narrowed portions ascams;

Fig 10 isa section along the lines I0-I0' of Fig. 9; and.

Fig. 11 is a sectionalelevation of a pressure device for forming ofhollow bodie which ine cludes, means for operation of the die closure bymeansof. the hydraulic fluid.

Referring now to the drawingsand in particular to Figs. 1 and 2, thedevice comprisesa die, I having a recess 2, which die, I may beclosedgby means of a cover 3'. The. latter is equipped with acentralization shoulder 4 which shoulder 4 engages a correspondingshoulder of thedie -I..

The cover 3-is secured tothe die by means of screw bolts 5.,which may beinserted in slotsdisposed in the cover 3 and may be tightened by meansofthe nutsb. A distancing ring I..is.disposed between the die. land thecover 3. By this arrangement an annular slot 8. is formed. Thedistancing ring I: is of. greater thickness than that of the metal sheetI0. disposed between the die andthe cover, in order to permit of asliding movement. for the, metal sheet I0 between the die and its cover.

The cover 3 is equipped with a connection boring for the-pressure pipeSen the die I is equipped with a, similar boring. leading to the suctionpipe II. Conduits which. may be closed by valve means lead from the saidpipesil and I I to a hydraulic pressurepump (not shown).

Any sheet metal may be used as a workpiece, for instance a simple planemetal sheet I!) may be disposed on the top face of the open" die. I:A'proper distancing ring-I brings: about theannular slot 8 uponpositioning, and tighteningof the cover. 3. by means of theboltsfit-and-units After this is done, the recesses on both sides of thesheet metal are filled with pressure fluid; Upon starting operation ofthe pump, thehydrau liev fiuid'exerts pressure in the. direction of thearrow I2 in the space I.3.of-.the cover, while at the same. time asuctioneffect isprovided' in the recess? of the die I; causing removalof the fluid in the recess 2 .in'the direction of the arrow I I; The.metal sheet is drawn into the recess 2 through the mentioned pressureand. vacuum operation; respectively. Duringthe drawing or forming,operation the portion ofthe metal sheet I0 disposed in theslotBfollowsthe forming-process by a sliding movement thereof in view of thefloating; of the, sheet metal on. a veil-thin. fluid layer. This processis continued until the: metal sheet is pressedfirmly toward the-wall ofthe recess:fyof-thedieal.

Upon opening of the device thefinished hollow body may be removedfrom-the die;

Instead of connecting. the suction pipe II to apump, it is also possibleto-providea safety valve, one end of which is preferably connected withatank disposedzona high level. V Y Y The-filling: up of. thedie may beachieved from such tank. Furthermore, the safety valve may 6. be used tosubjectthe fluid disposed in'the recess 2 of the die Itocontrollablecounter-pressure..

As shown inFig. 1, the-die I may be equipped with a sealing ring IS inorderto prevent the penetration of pressure fluid into-the recess 2 ofthe die I.

The sealing ring; I5, which is preferably made of rubber oranyothersuitablematerial; isthen disposed in an annularrecess iii of the-cover3. The sealing-ring I5-restsW'ith its preferably wide engaging faceon-the metal sheet I6.

Upon feeding the pressure fluid into the pres-'- sure pipe Sof the cover3; the sealing ring- I5 prevents the penetration of the hydraulic-fluidinto the annular slot- 8; thereby permitting the sliding of theyplane'sheet metal IOwithoutexertion of. the pressure: of the fluid andalso pre venting the overflow of the pressure fluid into the: recess 2'ofthe die I. It is also possible, to provide a second sealing ring IIbelow the fol-me ing radii, so that the edge of the metal sheet: I0engages firmly the wall of the recess? of the die, I even after leavingthe annular slotv 8 and also to prevent the entrance of the pressurefluid between the wall of the die I and the sheet metal;

The structure ofthe device shown inFig. 2. is substantially identicalwith that of Fig. 1' and comprises again a die I having. a recess Zwhichdie may be closed by acover 3'. The centralization shoulder t engages.-apropershould'erofithe die I to centralize the cover 3*, onthe die If.Borings are provided in the die. I and .cover 3" to remove. and. feed,respectively, thepressure fluid through. the pipes II and- 9. in the.direction-01 the arrows Id andIZ, respectively. Adistance ing ring 1'provides anannularspace between the die I and the cover 3-.

In the structure shown in'Fig. 2, the cover 3' has an annular recess I6which receivesaspring biased holding plate I9.

The recess 2., by example devised for the form.- ing of a bucket, isclosed up by the cover. 3. supported by the distancing ring I, therebysealing fluid-proof the recess 2 of the die I The holding plate, I9comprises a; highly polished. pressure member supported by an elasticbase I5 and isyieldingly maintained in thecover 3 by springs. 20.

Setscrews 21. which are disposed in liquid:- proof borings. 22; limit.the: movement of the holding: plate I9. I

The workpiece I G to be form-ediis-disposed between the upper face ofthe: die I and the holding-plate I9. The pressure force is chosen by themeasurement of the distancing ring, 1 in such manner that no foldsma-yform on the metal sheet. and stillsuch a space remains that a veil thinfluid layer provides. a small friction forthe movement, of the metalduring; the: forming process,

During. the pressing operation .thez'pressing fluid enters, in view ofthe very highapressure, the space below-theholding plate. I9 and alsoenters between the'meal. sheet and the'upper-facea of the die: I. Inthis manner, a fluid veil is formed between these faces, whicheliminates the friction between the workpiece and the die; despite thefact that the. holding plate I9, preventing the forming of folds in themetal sheet, isprovided.

Figs. 3, 4.1and 5 show. a structure of the device for forming. of hollowbodies-which are very deep in relationship to their diameter;

I The die I comprises a forming space 2 which leads into the upperplanesurface 23 0f the-dieblock by-means-bf a-rounded draw-breast I8 2The cover it rests on the die-block I by means of the distancing ring 1so that a slot 8 is formed the width of which is slightly larger thanthe thickness of the metal sheet. The bottom face of the cover 3receives an elastically yielding holding plate I9 The die-block I andthe cover 3 are connected together pressure-proof by any suitable means(not shown).

Furthermore, the cover 3 is equipped with an opening 24 extendingentirely therethrough in which a deep-drawing auxiliary piston 26oscillates and which auxiliary piston 26 is sealed by means of the seal25 The auxiliary piston 26 has a channel 21 which is adapted for feedingthe pressure fluid to the workpiece.

The forming space 2 is formed by a recess on the upper end of a tool 28and the latter reciprocates in an opening 29 of the die-block 1 The tool28 is formed as a differential piston by providing an upper portion ofsmaller diameter than that of its guiding lower portion 3I the latterbeing equipped with a packing. 30 The wall of the, opening 29 forms anannular shoulder 32 against which the guiding portion 31 of the tool 28abuts in its lifted position.

The opening 29 is closed up by a cover plate 33 the latter having achannel 34 which is adapted for feeding the counter-pressure fluid intothe die-block W.

The tool 28 is provided with a longitudinal boring 35 which leads fromthe opening 29 to the forming space 2 A second boring 38 leads from thementioned first boring 29 preferably in radial direction, to the outerwall of the tool 28 The second boring 36 terminates into a longitudinalslot 31 disposed along the entire length of the tool 28 and endingfreely at the upper end of the tool 28 The metal sheet I is positionedin the slot 8 (see Fig. 3) and upon feeding of counter-pressure fluidinto the opening 29 the tool 28 will be pressed into'itsuppermost'position, whereby also the forming space 2 is filled withcounter pressure fluid.

Thereafter, pressure fluid will be fed through the channel 21 and themetal sheet I0 will be drawn now into the forming space 2 in view of thehydraulic over-pressure. During this process the counter-pressure fluidwill be pushed out again. Small portions thereof will enter the slot 8while the main portion of the fluid will enter the opening 29 throughthe longitudinal boring 35 of the tool 28 Upon terminating the hydraulicdrawing process, which formed the metal sheet I9 to conform to the upperform of the tool 28 the auxiliary piston 26 is pressed downwardly (seeFig. 4) so that the head of the latter enters the tool 28 Upon furtherdownward pressure of the deepdrawing auxiliary piston 26 the tool 28starts its downward movement and the clamped workpiece is further drawn,thereby forming the cylindrical drawing piece.

During this drawing process the counterpressure fluid will be partlyremoved through the 7 drawing process, the auxiliary piston 26 iswithdrawn, the die-block is opened, and the finished workpiece isremoved.

Thereafter, a new plane metal sheet may be positioned on top of thedie-block l and the entire drawing process may be repeated in the samedescribed manner.

In order to form pre-formed hollow bodies, a device as disclosed inFigs. 6, '7 and 8 may be used.

In accordance with the present invention, the device comprises in thisstructure an upper die 40 and a lower die M which, upon insertion of theproperly pre-formed hollow cylinder 42 are drawn or pressed towards eachother.

Packings 43 are provided between the upper and lower dies 40 and 41Elastic end pieces 44 of rubber or any other suitable material aredisposed in the dies 40 and 41 at the ends of the hollow cylinder 42 Anannular groove 45 disposed in the dies 40 and M receives complementaryextensions of the end pieces to maintain the latter in position. Theguide slot 8 for the walls of the work cylinder 42 is formed between thedies 40 and M respectively, and the end pieces 44 The bottom of each ofthe end pieces 44 is screwed to the bottom of the corresponding bottomof the dies 40 and 4 i by means of sleeves 46 The sleeve 46 is alsoadapted for feeding the inner space 41 of the hollow cylinder 42 Thebottom of the end piece 44 is curved in inward direction and forms anannular flange 38 The outer face of the annular flange 48 is inclinedinwardly to the inner wall of the hollow cylinder 42 The space 41 in thehollow cylinder 42 and the inner space 2 in the dies 40 and M are atfirst filled with fluid without pressure through proper ventilating andfeeding conduits.

The drawing process is performed in the following manner: Pressure fluidis fed through the conduit 49 whereby care is taken that thecounter-pressure in the space 2 is always slightly lower than that ofthe pressure fluid.

The counter-pressure may be easily controlled by means of the safetyvalve 50 Fig. 7 shows the forming which may be achieved, by example,with a pressure up to one hundred atmospheres. The particular shape ofthe bottom of the end piece 44 which is curved inwardly operates like anangle lever under the suddenly appearing pressure, and the end piece 2-4is pressed thereby towards the bottom face M of the die. At the sametime the annular flange 48 engages with its outer face the end of thehollow cylinder 42 and seals the inner space 47 from the outer space 2having counter-pressure.

During the now starting forming process, the cylinder 42 is drawn awayfrom the bottom of the dies in the direction of the arrows (see Fig. '7)upon opening of the valve 50 a predetermined counter-pressure beingmaintained. The hollow cylinder 43 is thus drawn by expanding itscentral portion. A sudden increase of pressure on the gauge indicatesthat the pressing process is terminated.

The embodiment shown in Fig. 8 is adapted for forming of sheet metalswhich require a higher pressure than one hundred atmospheres. The dies40 and M may have the same shape as m the previously describedembodiment. The arrangement of conduits, pressure gauge and safety valvemay also be the same as in the previous embodiment. Yet, the end pieces44 are designed in such manner that they engage the bottom 5| 3 of thedies before pressure is applied.

1 Each of the end pieces is also screwed to the dies 40 and M by meansof a sleeve 46 In this embodimenmhowever, the bottom of a disc 52engagesthe-inner faceof theend piece 44 and the conically-shaped-outerface 53 of the disc 52 engages-theinnerface-of the end piece 44 Theouterfaceof-theflange of the end piece 44 engages thus the inner face ofthe hollow cylinder 42 to be formed.

Since in this structure both ends of thehollow cylinder 42 are-providedwith an end piece 44- two discs 52 are required. It .is preferable toconnectthe two discs 52 with a distancing ring 54 which is equippedwith. perforations .55 to per-mitof the feeding of pressure-fluidintothe innerspace 4'1 of the workpiece 42 The distance betweenthe discs52is chosen in such manner that when the hollow cylinder 52 is insertedinto thelower die M3, the discs 52 press the outer face 48 of the end.pieces "d'd towards the inner face of the lower cylinder "42 uponconnecting the twofdielhitlves 46 and-M During the drawing process theflange '48 of the send pieces 44 ispressed between the outer face of thedisc 52 and the inner'face of the hollow --.cylinder 42 and thereby agood scaling is brought about between .the pressure space and thecounter p'ressure"space.

As shown in Figs. 9 and I0, the die maybe devised for reducing thediameter of a cylindrical hollow body '56 to-form, for instance, milkcans or the like. In this case, the device is equipped with a lower die51 and an upper die 58 which hasanextension. 6B. The latter reachestothe bottom 60 of the pre-forme'd body 55 and'is disposedconcentrically in the recess space 59 of the'upper die 58. .Cores 62 aredisposed next to the-extension whiczhizoic'es'iiz determine the narrowedshapeof the workpiece in its final form. A slot 8 is formed at the upperend of the space 59 of the upper die 58 which slot 8 receives the upperedge of the workpiece 56 and is also equipped, as in the previouslydescribed embodiments with a packing I5 Upon feeding pressure fluid intothe pressure space I3 a predetermined portion of the workpiece is drawninwardly, whereby the portion of the workpiece cylinder disposed in theslot 8 may slide out from the latter.

The device shown in Fig. 11 comprises a frame 66 which is supported by abase plate 85 and which carries a block 61 The latter receives thehydraulically operated and hydraulically locked die. The block 51 has arecess in which the die I is exchangeably inserted, the die I having theforming recess 2 The block 61 has a flat upper face 68 which is flushwith the upper face of the die 1 The flat face 68 of the block 61 isformed to an outer guide edge 69 extending above the face 68 the guideedge being adapted to guide the cover 3 into position. For this purposethe cover 3 is equipped with a corresponding face 4 which engages theinner face of the guide edge 69 Furthermore, the cover it is equippedwith an upper flange N which extends over the periphery of the block 61The upper face 68 of the block 6'1 has a groove which receives thedistancing ring 1 The bottom face of the cover 3 has preferably anelastic packing ring I5 A housing H which surrounds the frame 66 as wellas the block 61 resting thereon, is also disposed on the base plate 65The housing H has bottom flanges 12 to which hydraulic cylinders 13 aresecured by any convenient means. Piston rods extending from the pistons14 which reciprocate in the cylinders 13 extend zontal directionopposite the 'block 67 H Each.piston 18 reciprocating .in the cylinder17 carries a piston rod 79 the end of Twhich is enforced to abolt '8llwhich reciprocatesin an opening .81 of 'the .guideedge 69 of --the block6-7 A:bor ing 82 -coaxially disposed with the axis of the bolt '80-extends through thefacedithere- .by-locking the cover :3 in closingposition. A plurality-of such locking means is disposed onthecircumeference of the block 61 The space above the top of the metalsheet I0 is connected with a-hydraulic accumulator or the likeby meansof the conduit 8 The die recess 2 is also connected with an accumulatorby means of the conduit H The drawing process is brought aboutby'feeding pressure fluid-to the workpiece and removing thecounter-pressure fluid in the same manner as described above inconnection with the other embodiments.

In order-to deposit in the forming device a workpiece, as a metal sheet0 the'control-device 83 causes the feeding of pressure fluid from theconduitSl through the'conduit 84 intothe hydraulic cylinder 11 and inparticular in front of the piston I -8 By this means the bolt 8ll :iswithdrawn and is removed from the openingsti! of the cover 3 I Nowanother control device "85 causes the feeding of the pressure fluidfromthe'c'o'nduitlll through the conduits 86 into thehyd'raulic cylinder 13The piston 14 is lifted by the pressure e'xertedby thehy'draulic'fluid'and thepiston rod 15 secured to the piston 14 lifts"thecover 3 from the'block 61 The feeding of a new workpiece or theremova of a finished workpiece may be achieved in the raised position ofthe cover 3 Upon lowering of the cover 3 the forming device is olosedagain. The closing step may be achieved by the own gravity of theelements to be lowered, whereby the pressure fluid is removed freely orthe pressure fluid can be sucked off in order to accelerate the closingstep. When the cover 3 reaches its closing position, the shifting of thecontrol device 83 causes the feeding of pressure fluid behind thepistons 78 of the hydraulic cylinders (1 and accordingly the bolts 80are moved into the openings 82 of the cover 3 In this position theforming device is ready again for the next forming process.

While I have disclosed several embodiments of the present invention, itis to be understood that these embodiments are given by example only andnot in a limiting sense, the scope of the present invention beingdetermined by the objects and the claims.

I claim:

1. The device for forming hollow bodies from a working element underhydraulic pressure comprising a pressure die, having an operativepressure face and having means for feedin pressure fluid to the pressureside of the Said pressure die, the said feeding means terminating in thesaid operative pressure face of the said pressure die, and a forming diedefining a forming chamber of a shape conforming to that to be formedfrom the said working element and having a shoulder surrounding the saidchamber of the said forming die, the said chamber having fluid underpressure therein, a sealin ring carried by and extending beyond theoperative pressure face of the said pressure die, disposed opposite thesaid shoulder of the Said forming die, and engaging the face of the saidworking element, a distancing ring disposed at the periphery of the saidshoulder of the said forming die spacing apart the latter from the saidpressure die a distance which is greater than the thickness of the saidworking element together with that portion of the said sealing ringextending beyond the said operative pressure face of the said pressuredie to provide space for a veil-thin layer of hydraulic fluid betweenthe said working element and the said shoulder of the said formingmember and to surround the edge portion of the said working element Withthe pressure fluid of the said forming chamber, the said pressureprevailing in the said pressure die being greater than that prevailingin the Said forming die, so that the pressure fluid from the saidpressure die will engage the face of the said working element within thelimits of the said Sealing ring, while the same face of the said Workinelement outside the limits of the said sealing ring and the oppositeface of the said working element is engaged by the fluid of the saidforming chamber and a veil-thin layer of pressure fluid from the saidforming chamber is disposed between the said opposite face of the saidworking element and the shoulder of the said forming die.

2. The device, as set forth in claim 1, in which the said sealing membercomprises an elastic ring which is pressed against the said face of thesaid working element.

3. The device, as set forth in claim 2, in which the said elastic ringcomprises a holding plate, a plurality of springs disposed in the saidpressure die and yieldingly pressing against the said holding plate, andin which the said pressure die has axially disposed threaded borings andset screws threaded in the said borings and engaging the said holdingplate, the said set screws being adjusted from the outer face of thesaid pressure die through the said threaded boring to limit the positionof the said holding plate.

4. The device, as set forth in claim 1, which device is adapted to formhollow bodies from a working element consisting of a hollow tubularmember, in which the said sealing ring comprises an end piece disposedat the open end of the said hollow tubular member in order to seal oilthe pressure prevailing in the said pressure die from the pressureprevailing in the forming die, the said end piece having an angularflange projecting into the open end of the said hollow tubular memberand the said angular flange engaging the inner face of the said hollowtubular member upon applying pressure into the said pressure die.

HEINRICH EWALD KRANENBERG.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,522,051 Fulton et a1. Jan. 6, 1925 2,038,304 Middler Apr.21, 1936 2,082,199 Dake June 1, 1937 2,284,773 Sivian et a1 June 2, 19422,289,584 McMillin et a1. July 14, 1942 2,348,921 Pavlecka May 16, 19442,407,855 Stephens Sept. 17, 1946 2,399,775 Whistler et a1. May 7, 19462,417,794 Werner Mar. 18, 1947 2,531,539 Smith Nov. 28, 1950

